Abstract The purpose of this study is to develop and pilot test a novel group-level intervention to reduce sexual risk behavior and increase HIV testing among heterosexually active African American men. Heterosexually active men have been called the "forgotten group" in HIV prevention, with the bulk of interventions focusing on women or other groups at high risk of HIV. In the United States, heterosexual contact is currently the second highest mode of HIV acquisition and African Americans are over-represented among these cases. New York City is the metropolitan area with the largest number of AIDS cases among African American men attributed to heterosexual contact. We propose a mixed-method study among adult heterosexually active African American men living in high prevalence neighborhoods with the aims to: 1) explore through in-depth qualitative interviews and focus groups personal, behavioral, and socio-structural factors that affect HIV sexual risk behavior and HIV testing rates, and participant perspectives on intervention characteristics; 2) develop and pilot test the intervention; and 3) estimate the efficacy of the intervention on reducing sexual risk behaviors and increasing HIV testing. To achieve these aims, we propose to conduct 6 focus groups and 50 in-depth interviews to elicit: (a) descriptions and reflections on personal, behavioral and socio-structural factors that impact on HIV sexual risk behavior and HIV testing. These factors will be examined from a general perspective and through questions that elicit descriptions, reflections, and comparisons of past sexual risk events, both high and low risk, and the factors affecting the course of those events; (b) participant perspectives on intervention characteristics that may effectively lead to reductions in high risk behavior and increases in HIV testing. We will then develop and pilot test a multi-session group-level intervention informed by the findings of our formative research, and pilot test the interview instrument. In the last phase, we will conduct a pre-post test study by enrolling 50 heterosexually active African American men at risk of HIV infection into the intervention. At baseline and 3 months, standardized data collection using audio computer assisted self-interviewing technology will assess outcomes and covariates. The primary outcomes for the estimating efficacy will be the occurrence of unprotected vaginal intercourse and/or unprotected anal intercourse with female partners and concurrent partnering with female and/or male partners. Secondary outcomes will include occurrence of HIV testing and number of new and total female and male sex partners. The results of this proposed project will be used to estimate sample size or effect size for scaling up to a randomized controlled trial. The heterosexual HIV epidemic is a growing public health problem in the United States. African Americans are over-represented among these cases, contributing to the growing health disparities that characterize the HIV epidemic in the US. This study will develop and test a behavioral intervention to reduce sexual risk and increase HIV testing among heterosexually active African American men. [unreadable] [unreadable] [unreadable]